ORCID Profile
0000-0002-5264-3142
Current Organisation
La Trobe University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Oxford University Press (OUP)
Date: 07-12-2018
DOI: 10.1093/AOB/MCY167
Publisher: Elsevier BV
Date: 03-2021
Publisher: Elsevier BV
Date: 05-2015
Publisher: Research Square Platform LLC
Date: 05-05-2023
DOI: 10.21203/RS.3.RS-2871656/V1
Abstract: In iduals may add to their behavioural repertoire by observing conspecifics, and possibly heterospecifics. Here we test Darwin’s intriguing hypothesis that honey bees rob nectar from flowers after observing the behaviour of other bees. We trained naïve honey bees to forage for sucrose by entering the flower-tube opening of custom designed 3D-printed model flowers before exposing in idual bees to experimental flowers. In these flowers, nectar could only be accessed via a small hole at the base of the corolla tube, thereby simulating secondary nectar-robbing. Bees had to change their foraging behaviour from foraging via the mouth of the flower to foraging from the tube-base to rob. Different demonstrators were used to indicate the presence of a robbing hole. To explore the efficiency of information transfer from different demonstrators, we moved dead conspecific and heterospecific (carpenter bees and crickets) demonstrators towards this small hole to imitate nectar robbing. Differences in the ability and speed of honey bees to imitate robbing behaviour were recorded for each demonstrator treatment. Naïve honey bees switched to robbing behaviour more frequently when observing honey bee and carpenter bee demonstrators than when observing cricket demonstrators or controls that lacked a demonstrator. However, honey bees switched to robbing behaviour significantly faster after observing conspecifics than after observing any other demonstrators. This study demonstrates that honey bees can gather information from conspecifics and even heterospecifics while foraging, which can influence foraging behaviour such as flower robbing. Utilizing foraging cues from other in iduals may lead to conspecific and heterospecific learning. “I can hardly doubt they [honeybees] were profiting by the workmanship and the ex le of the humble-bees: should this be verified, it will, I think, be a very instructive case of acquired knowledge in insects.” Darwin 1841
Publisher: Elsevier BV
Date: 05-2015
Publisher: Cold Spring Harbor Laboratory
Date: 16-02-2019
DOI: 10.1101/551523
Abstract: Animal-mediated pollination is an essential ecosystem service which over a third of the world’s agricultural crops depend on. Blueberry fruit production is highly dependent on pollinators and in their native range they are pollinated mostly by bumble bees ( Bombus spp.). Demand for blueberries has increased in recent years due to their perceived health benefits. Consequently, blueberry cultivation has expanded well beyond their native range, including several regions where bumble bees are not present. In many areas, honey bees may be the only commercially available pollinators of blueberries because many countries ban the importation of bumble bees. This study aimed to determine the benefits of honey bee pollination on blueberry fruit quality and quantity for the variety Ventura by comparing yields of honey-bee-pollinated flowers to flowers where pollinators had been excluded. Honey bees significantly increased berry mass and diameter. Our results suggest that the presence of honey bee pollinators potentially increases revenue by approximately $864 501/ha in areas without bumble bees. We conclude that Ventura is reliably pollinated by honey bees, and that honey bee pollination may be a useful substitute for bumble bees in areas where bumble bees are absent. We also determined the extent to which blueberry yields could still be improved by comparing fruit quality and quantity under honey bee pollination to fruit quality and quantity achieved through ideal hand pollination. We found that blueberry yields may be still be significantly increased relative to ideal hand pollination and we discuss potential ways to improve the efficiency of honeybee pollination in the future. Additional research is required to study how beneficial honey bees are to fruit yield on varieties as the benefits of honey bees are likely to vary across different varieties.
Publisher: Wiley
Date: 30-10-2019
DOI: 10.1111/BRV.12564
Abstract: Biological mimicry has served as a salient ex le of natural selection for over a century, providing us with a dazzling array of very different ex les across many unrelated taxa. We provide a conceptual framework that brings together apparently disparate ex les of mimicry in a single model for the purpose of comparing how natural selection affects models, mimics and signal receivers across different interactions. We first analyse how model-mimic resemblance likely affects the fitness of models, mimics and receivers across erse ex les. These include classic Batesian and Müllerian butterfly systems, nectarless orchids that mimic Hymenoptera or nectar-producing plants, caterpillars that mimic inert objects unlikely to be perceived as food, plants that mimic abiotic objects like carrion or dung and aggressive mimicry where predators mimic food items of their own prey. From this, we construct a conceptual framework of the selective forces that form the basis of all mimetic interactions. These interactions between models, mimics and receivers may follow four possible evolutionary pathways in terms of the direction of selection resulting from model-mimic resemblance. Two of these pathways correspond to the selective pressures associated with what is widely regarded as Batesian and Müllerian mimicry. The other two pathways suggest mimetic interactions underpinned by distinct selective pressures that have largely remained unrecognized. Each pathway is characterized by theoretical differences in how model-mimic resemblance influences the direction of selection acting on mimics, models and signal receivers, and the potential for consequent (co)evolutionary relationships between these three protagonists. The final part of this review describes how selective forces generated through model-mimic resemblance can be opposed by the basic ecology of interacting organisms and how those forces may affect the symmetry, strength and likelihood of (co)evolution between the three protagonists within the confines of the four broad evolutionary possibilities. We provide a clear and pragmatic visualization of selection pressures that portrays how different mimicry types may evolve. This conceptual framework provides clarity on how different selective forces acting on mimics, models and receivers are likely to interact and ultimately shape the evolutionary pathways taken by mimetic interactions, as well as the constraints inherent within these interactions.
Publisher: Elsevier BV
Date: 05-2013
Publisher: Oxford University Press (OUP)
Date: 07-06-2018
DOI: 10.1093/AOB/MCY083
Publisher: Cold Spring Harbor Laboratory
Date: 21-08-2019
DOI: 10.1101/742114
Abstract: Blueberry plants require large quantities of pollen deposited on stigmas to produce commercial-quality fruit. Like many agricultural crops, the interaction between pollen-source variety and pollen-recipient variety can be a major determinant of fruit quality in blueberries. However, little information exists to guide growers in optimising fruit set and quality. Using five commonly grown blueberry varieties, I determined whether crossing between varieties (inter-varietal) increased fruit mass and decreased developmental time relative to crossing within a variety (intra-varietal), and if so, what the best crossing combinations are. While intra-varietal pollination often produced fruit, for certain varieties the fruit set and fruit mass were highly reduced compared to inter-varietal pollination. Furthermore, intra-varietal pollination resulted in longer fruit developmental time in comparison to pollination between varieties. For the same pollen-recipient variety, inter-varietal crosses typically outperformed intra-varietal crosses in fruit mass and developmental time however, the extent to which inter-varietal crosses outperformed intra-varietal crosses differed between pollen-donor varieties. This result suggests that combinations of varieties are not trivial as some inter-varietal combinations may outperform others. Furthermore, some varieties appear to be more susceptible to the negative effects of intra-varietal crosses than others and that less susceptible varieties may be better suited to conditions where pollinator movement is poor. While our study can guide growers in determining optimal co-planting schemes for the varieties tested, for ex le in South Africa where these varieties are frequently grown. It also serves as a blueprint for similar compatibility studies that can easily be performed prior to planting to determine the best inter-varietal combinations.
Publisher: The Royal Society
Date: 22-03-2014
Abstract: The costs that species suffer when deceived are expected to drive learned resistance, although this relationship has seldom been studied experimentally. Flowers that elicit mating behaviour from male insects by mimicking conspecific females provide an ideal system for such investigation. Here, we explore interactions between a sexually deceptive daisy with multiple floral forms that vary in deceptiveness, and the male flies that pollinate it. We show that male pollinators are negatively impacted by the interaction, suffering potential mating costs in terms of their ability and time taken to locate genuine females within deceptive inflorescences. The severity of these costs is determined by the amount of mating behaviour elicited by deceptive inflorescences. However, inexperienced male flies exhibit the ability to learn to discriminate the most deceptive inflorescences as female mimics and subsequently reduce the amount of mating behaviour they exhibit on them with increased exposure. Experienced males, which interact with sexually deceptive forms naturally, exhibit similar patterns of reduced mating behaviour on deceptive inflorescences in multiple populations, indicating that pollinator learning is widespread. As sexually deceptive plants are typically dependent on the elicitation of mating behaviour from male pollinators for pollination, this may result in antagonistic coevolution within these systems.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Wiley
Date: 11-05-2019
Publisher: Elsevier BV
Date: 10-2009
Publisher: Wiley
Date: 31-07-2012
Publisher: Oxford University Press (OUP)
Date: 19-09-2013
DOI: 10.1093/AOB/MCT189
Publisher: Elsevier BV
Date: 04-2009
Publisher: The Royal Society
Date: 19-08-2014
Abstract: Phenotypic integration, the coordinated covariance of suites of morphological traits, is critical for proper functioning of organisms. Angiosperm flowers are complex structures comprising suites of traits that function together to achieve effective pollen transfer. Floral integration could reflect shared genetic and developmental control of these traits, or could arise through pollinator-imposed stabilizing correlational selection on traits. We sought to expose mechanisms underlying floral trait integration in the sexually deceptive daisy, Gorteria diffusa , by testing the hypothesis that stabilizing selection imposed by male pollinators on floral traits involved in mimicry has resulted in tighter integration. To do this, we quantified patterns of floral trait variance and covariance in morphologically ergent G. diffusa floral forms representing a continuum in the levels of sexual deception. We show that integration of traits functioning in visual attraction of male pollinators increases with pollinator deception, and is stronger than integration of non-mimicry trait modules. Consistent patterns of within-population trait variance and covariance across floral forms suggest that integration has not been built by stabilizing correlational selection on genetically independent traits. Instead pollinator specialization has selected for tightened integration within modules of linked traits. Despite potentially strong constraint on morphological evolution imposed by developmental genetic linkages between traits, we demonstrate substantial ergence in traits across G. diffusa floral forms and show that ergence has often occurred without altering within-population patterns of trait correlations.
Publisher: Elsevier BV
Date: 07-2022
Publisher: Springer Science and Business Media LLC
Date: 11-08-2016
Publisher: Wiley
Date: 16-09-2015
Publisher: Elsevier BV
Date: 04-2010
Publisher: Wiley
Date: 24-07-2019
DOI: 10.1111/NPH.15971
Abstract: The causative link between phenotypic ergence and reproductive isolation is an important but poorly understood part of ecological speciation. We studied the effects of floral-tube length variation on pollen placement/receipt positions and reproductive isolation. In a population of Lapeirousia anceps (Iridaceae) with bimodal floral-tube lengths, we labelled pollen of short- and long-tubed flowers with different colour fluorescent nanoparticles (quantum dots). This enabled us to map pollen placement by long- and short-tubed flowers on the only floral visitor, a long-proboscid fly. Furthermore, it allowed us to quantify pollen movement within and between short- and long-tubed flowers. Short- and long-tubed flowers placed pollen on different parts of the pollinator, and long-tubed flowers placed more pollen per visit than short-tubed flowers. This resulted in assortative pollen receipt (most pollen received comes from the same phenotype) and strong but asymmetric reproductive isolation, where short-tubed plants are more reproductively isolated than long-tubed plants. These results suggest that floral-tube length ergence can promote mechanical isolation in plants through ergence in pollen placement sites on pollinators. Consequently, in concert with other reproductive isolation mechanisms, selection for differences in floral-tube length can play an important role in ecological speciation of plants.
Publisher: Elsevier BV
Date: 02-2017
DOI: 10.1016/J.YMPEV.2016.12.004
Abstract: The Greater Cape Floristic Region (GCFR) in South Africa has been extensively investigated for its phenomenal angiosperm ersity. A key emergent pattern is the occurrence of older plant lineages in the southern Fynbos biome and younger lineages in the northern Succulent Karoo biome. We know practically nothing, however, about the evolutionary history of the animals that pollinate this often highly-specialized flora. In this study, we explore the evolutionary history of an important GCFR fly pollinator, Megapalpus capensis, and ask whether it exhibits broadly congruent genetic structuring and timing of ersification to flowering plants within these biomes. We find that the oldest M. capensis lineages originated in Fynbos during the Miocene, while younger Succulent Karoo lineages erged in the Pliocene and correspond to the proposed age of this recent biome. A strong signature of population expansion is also recovered for flies in this arid biome, consistent with recent colonization. Our first investigation into the evolutionary history of GCFR pollinators thus supports a recent origin of the SK biome, as inferred from angiosperm phylogenies, and suggests that plants and pollinators may have co- erged within this remarkable area.
Publisher: Springer Science and Business Media LLC
Date: 19-12-2010
DOI: 10.1007/S00442-010-1879-7
Abstract: The co-occurrence of plant species within a community is influenced by local deterministic or neutral processes as well as historical regional processes. Floral trait distributions of co-flowering species that share pollinators may reflect the impact of pollinator preference and constancy on their assembly within local communities. While pollinator sharing may lead to increased visitation rates for species with similar flowers, the receipt of foreign pollen via interspecific pollinator movements can decrease seed set. We investigated the pattern of community flower colour assembly as perceived by native honeybee pollinators within 24 local assemblages of co-flowering Oxalis species within the Greater Cape Floristic Region, South Africa. To explore the influence of pollinators on trait assembly, we assessed the impact of colour similarity on pollinator choices and the cost of heterospecific pollen receipt. We show that flower colour is significantly clustered within Oxalis communities and that this is not due to historical constraint, as flower colour is evolutionarily labile within Oxalis and communities are randomly structured with respect to phylogeny. Pollinator observations reveal that the likelihood of pollinators switching between co-flowering species is low and increases with flower colour similarity. Interspecific hand pollination significantly reduced seed set in the four Oxalis species we investigated, and all were dependant on pollinators for reproduction. Together these results imply that flower colour similarity carries a potential fitness cost. However, pollinators were highly flower constant, and remained so despite the extreme similarity of flower colour as perceived by honeybees. This suggests that other floral traits facilitate discrimination between similarly coloured species, thereby likely resulting in a low incidence of interspecific pollen transfer (IPT). If colour similarity promotes pollinator attraction at the community level, the observed clustering of flower colour within communities might result from indirect facilitative interactions.
Publisher: Wiley
Date: 28-02-2013
DOI: 10.1111/EVO.12070
Abstract: Divergent mate preferences and subsequent genetic differentiation between populations has been demonstrated, but its effects on interspecific interactions are unknown. Associated species exploiting these mate preferences, for ex le, may erge to match local preferences. We explore this idea in the sexually deceptive, fly-mimicking daisy, Gorteria diffusa, by testing for association between genetic structure in the fly pollinator (a proxy for mate preference ergence) and geographic ergence in floral form. If genetic structure in flies influences interactions with G. diffusa, we expect phylogeographically distinct flies to be associated with different floral forms. Flies associated with forms exploiting only feeding behavior often belonged to several phylogeographic clades, whereas flies associated with forms exploiting male-mating behavior always belonged to distinct clades, indicating the possibility of pollinator-mediated floral ergence through phylogeographic variation in mating preferences of male flies. We tested this hypothesis with reciprocal presentations using male flies from distinct clades associated with separate floral forms. Results show that males from all clades exhibit similar preferences, making pollinator driven ergence through geographic variation in mate preference unlikely. Males, however, showed evidence of learned resistance to deceptive traits, suggesting antagonistic interactions between plants and pollinators may drive deceptive floral trait evolution in G. diffusa.
Publisher: Springer Science and Business Media LLC
Date: 09-02-2016
No related grants have been discovered for Marinus De Jager.